Whats the difference in A/B vs A/D ?

[hispls]

D-Class is a bunch of amplified square waves as where A, A/B, B, and a bunch of other class amplifiers are not.

A-Class sends the entire sound wave (360 degrees) through the transistors which creates A LOT of heat and stresses the components. There is no switching between different transistors to get the positive wave and negative wave, which is really nice for audio. You just have to be in a situation where you only need about 20-30W of power.

B-Class amplifiers have a positive set of transistors and a negative set of transistors. Each side will have half of the sound wave (180 degrees each) be sent through them to be amplified. The top half of the wave (0-179 degrees) will go through the positive transistors while the bottom half (180-359 degrees) will go through the negative transistors. This allows for higher power ratings as you have essentially cut the amount of time that the transistors have to work in half.

A/B-Class amplifiers are a mixture of both A-Class and B-Class, this means that there are still a positive set and a negative set of transistors. The transistors in this topology with have somewhere from 181 degrees of a wave sent through them to 359 degrees of the wave sent through. This creates an overlap in the output to avoid any negative affects from the transistors at the end of their cycles. I personally don't like A/B-Class as there are some problems that arise in the topology that are easily fixed by just switching to B-Class. What the classification has turned into is a large marketing technique as people think that having an A/B amp is getting them closer to an A-Class amp, in the end a lot of "A/B-Class" amps end up just being B-Class.

D-Class is a topology that uses a whole different design process that goes from using linear transistors to lateral transistors. In the end what the topology does is use square waves of varying time highs (the amount of time the signal is sent) to mimic different levels of sound. Short bursts are used to recreate the middle of the wave while long bursts are used to recreate the wave when it should have the highest voltage. To do this you have to also have a switching process to go on which is normally around 1000Hz (this is where the burnt leads issue came about). By the time you get to the end of the board the sound is all jacked up and has multiple different frequencies all piled up on each other ranging way far up past 20 KHz, to try and lessen the damage done by this capacitors are used to try and filter out some of the upper frequencies that are produced. From all of the negatives of the sound quality of D-Class there are a couple of good qualities, the size of the amp to have a large output is stupid small, and the transistors are able to output huge amounts of wattage due to being so efficient.

Tomorrow or so I can try and get some visuals to help the people that it just isn't really clicking for.

You really need to catch up with the times with regards to class D. I think you'll be very hard pressed to find an amp that uses a 1000hz carrier. In fact, the technology to make a good sounding, low distortion class D amp has been around a good long time and I'd say in the last decade the companies who actually do R&D and the better engineers have produced full range class D amps that sound just as good as any A or B class.

I really encourage you to go out and audition some of the higher quality PWM designs available today.

At this point the ONLY reason not to use class D is that the cost is still rather high as far as dollars per watt for the ones that are really done right.

[Krakin]

You really need to catch up with the times with regards to class D. I think you'll be very hard pressed to find an amp that uses a 1000hz carrier. In fact, the technology to make a good sounding, low distortion class D amp has been around a good long time and I'd say in the last decade the companies who actually do R&D and the better engineers have produced full range class D amps that sound just as good as any A or B class.

I really encourage you to go out and audition some of the higher quality PWM designs available today.

At this point the ONLY reason not to use class D is that the cost is still rather high as far as dollars per watt for the ones that are really done right.

I do believe that they have gotten better, but I haven't had much time the last couple of months to keep ready books on them, I don't have the money as all of it it pretty much going to college now.

When I can see/hear definitive proof that they sound as good I'll change my opinion.

It is just hard to gauge sound quality from the internet, as there is no sound quality meter.

[gckless]

I haven't heard the new RF ad amps but they are saying that it has class ab sq with class d efficiency and constant power topologies. Think I read somewhere that they're calling it there best sounding amp to date.

With a catch lol. They did produce the T-15k. I cannot for a second believe a class D have any sound quality.

If you want someone to rant about it just ask Tony D. Haha.

I will admit that I need to learn more about it, but in no way will it be their best sounding amp.

Zed Audio uses switching frequencies at close to 500KHz. This is a really good read up to about page 18 or so if you have the time man: http://www.zedaudiocorp.com/pdfs/ZedManual-2012.pdf

It's not all about Zed, but a lot of general, intelligent info. Stephen Mantz is a super smart dude.

I will also invite you to listen to my Leviathan anytime we can meet at a show or otherwise. Running at 8 ohms, she sounds pretty sweet. I think you would be surprised.

Here's a blind test that was done: http://www.caraudiojunkies.com/showthread.php?483-AMplifer-A-B-Blind-testing-Time-to-hear-for-myself!&p=11355&viewfull=1#post11355

Post #39 has results. I hope the link will stay, it's a pretty invaluable test.

[Krakin]

Zed Audio uses switching frequencies at close to 500KHz. This is a really good read up to about page 18 or so if you have the time man: http://www.zedaudiocorp.com/pdfs/ZedManual-2012.pdf

It's not all about Zed, but a lot of general, intelligent info. Stephen Mantz is a super smart dude.

I will also invite you to listen to my Leviathan anytime we can meet at a show or otherwise. Running at 8 ohms, she sounds pretty sweet. I think you would be surprised.

Here's a blind test that was done: http://www.caraudiojunkies.com/showthread.php?483-AMplifer-A-B-Blind-testing-Time-to-hear-for-myself!&p=11355&viewfull=1#post11355

Post #39 has results. I hope the link will stay, it's a pretty invaluable test.

I could get the full results downloaded, however the first link was a dud for me, but I found it through their site anyway.

After I get settled in with my move to the university and get my schedule all down I can find time to read up some more on the D-Class technology.

[hispls]

You really need to catch up with the times with regards to class D. I think you'll be very hard pressed to find an amp that uses a 1000hz carrier. In fact, the technology to make a good sounding, low distortion class D amp has been around a good long time and I'd say in the last decade the companies who actually do R&D and the better engineers have produced full range class D amps that sound just as good as any A or B class.

I really encourage you to go out and audition some of the higher quality PWM designs available today.

At this point the ONLY reason not to use class D is that the cost is still rather high as far as dollars per watt for the ones that are really done right.

I do believe that they have gotten better, but I haven't had much time the last couple of months to keep ready books on them, I don't have the money as all of it it pretty much going to college now.

When I can see/hear definitive proof that they sound as good I'll change my opinion.

It is just hard to gauge sound quality from the internet, as there is no sound quality meter.

You need to get out to some more shows and meetups then. Or even go out to your local Home Theater store and listen to some home theater PWM receivers. Seriously, your thinking on the whole theory is 20 years out of date.

The companies like JL, Zed, Zapco, Arc, and even the Alpine (apart from their first gen full range class D's) are all implementing full range class D that would be indistinguishable from B and I'd go as far as to say the better ones from the better engineers will probably sound BETTER than the typical buck a watt class B amps coming out of China and Korea being sold under brand names people have a hardon over.

[Krakin]

I will completely agree on a good design beating anything that doesn't have someone caring behind it.

The only problem is that when I start to get into the technical side of amplifier design I have to start looking up and learning about something else by page 5 because I haven't heard the term before.

So far I am about 2 years or so in of self teaching (from the interwebz) on my electrical knowledge, which is where my old knowledge of the D-Class comes from.

I completely admit to being ignorant about much of the designs past the few books I've gotten somewhat through.

I was going to head out to heatwave, but my family decided to come in from Austin Texas on those days.

Also my audio shop here is full crap and uses the twist it method for their wiring, they also don't carry anything of any quality.

[Smoove]

This is a good read. Keep the info coming. As Alaskanzx5 stated, what about something like RF's A/D? Is A/D technology the future of SQ?

[CleanSierra]

I've heard of a few advocates and that "in crowd" SQ competitors making a switch to these newer, quality D full range amps and that are winning with them. Just like how you've seen a switch go from purely sealed for Sound quality comps, to well thought out, low tuned, efficient designed enclosures.

[alaskanzx5]

Sq is still subjective and can be achieved with some of the lower end or even non sq equipment with great staging and tuning.

So in other words the class of the amp doesn't make it or break it for sq but the time and effort put into it does. Sure a class a, b or ab amp might make it a bit easier but its still very much so dependant on the person doing the install.

[Krakin]

That makes sense until you get a perfect install then check to see what amps are better.

Sound quality should not be subjective. Sound quality should be solely objective with the goal to recreate the sound as close as physically possible to how it was recorded.

You don't use the Ear-o-meter to win SPL competitions.

When you bring subjectivism into science you get things such as this.

In 1903, Rene Blondlot, a respected French physicist, claimed to have discovered a new form of radiation he called ‘ N-rays ’ . (This was shortly after the discovery of X-rays by Roentgen, so rays were in the air, as it were.) This invisible radiation was apparently mysteriously refracted by aluminum prisms; but the crucial factor was that its presence could only be shown by subjective assessment of the brightness of an electric arc allegedly affected by N-rays. No objective measurement appeared to be possible. To Blondlot, and at least 14 of his professional colleagues, the subtle changes in brightness were real, and the French Academy published more than 100 papers on the subject.

Unfortunately N-rays were completely imaginary, a product of the ‘ experimenter-expectancy ’ effect. This was demonstrated by American scientist Robert Wood, who quietly pocketed the

aluminum prism during a demonstration, without affecting Bondlot’s recital of the results. After this the N-ray industry collapsed very quickly, and while it was a major embarrassment at the time,

it is now almost forgotten.

The conclusion is inescapable that it is quite possible for large numbers of sincere people to deceive themselves when dealing with subjective assessments of phenomena.

From The Audio Power Amplifier Design Handbook, 5th Ed

http://www.barnesandnoble.com/listing/2682913334601?r=1&cm_mmc=GooglePLA-_-TextBook_NotInStock_26To75-_-Q000000633-_-2682913334601